U.S. Senator Susan Collins has been critical of the Senate's healthcare bills. Thomson Reuters The GOP healthcare bill faces an uncertain future in the Senate as it goes up for a vote Tuesday.

The Senate is expected to vote on a motion to proceed that would bring up the healthcare bill that passed in the House. At that point, one of a number of proposed draft healthcare bills stands to be shaped into the legislation that will get voted on.

Even so, many Republican senators have not embraced the bill with open arms.

Some more conservative senators want to vote on a bill to fully repeal the Affordable Care Act, or Obamacare. Some moderates, on the other hand, think the bill to repeal and replace, the Better Care Reconciliation Act (BCRA), goes too far and want to keep some of the more popular parts of the ACA intact.

Here are the GOP senators who have shaped the fight over the Senate healthcare bill — and what they might still want to change.

1/

Dean Heller of Nevada

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What he's said: Heller faces a tight reelection bid in 2018 in a state that recently passed a bill, which was eventually vetoed by the governor, to expand Medicaid access to everyone in Nevada. He opposed a previous version of the bill, but hasn't taken a definitive stance on more recent drafts.

What he wants: Heller took issue with the proposed phaseout of the Medicaid expansion and the funding growth-rate formula.

2/

Susan Collins of Maine

Susan Collins.
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What she's said: A week ago, Collins opposed a motion to proceed on a vote on the BCRA and the repeal-only bill. Since then, she hasn't appeared to change her mind. Throughout the process she has been critical of the BCRA and its changes to the Medicaid program.

Collins also isn't a fan of the approach to vote on a motion to proceed on the bill before knowing exactly which bill will be voted on. ""I don't think that's a good approach to facing the legislation that affects millions of people and one-sixth of our economy," she said on Sunday.

What she wants: While Collins' state has not expanded Medicaid, the slower growth caps for the program could be enough to push her away from the bill. Additionally, Collins opposes defunding Planned Parenthood, which the Senate bill would do for one year. Collins' term is up in 2020.

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Rand Paul of Kentucky

Rand Paul.
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What he's said: Paul was among the four senators that came out publicly against the BCRA in June, arguing that it did not deliver on its promise to repeal Obamacare. A bill to repeal the ACA is now on the table, and Paul supports that one, though he's still not in favor of the BCRA.

What he wants: Paul wants to roll back much of the regulations set up by the ACA and eliminate much of the funding to provide insurance subsidies. He said during the legislation's drafting of the bill that he doesn't want to create "a new entitlement" by solidifying the tax credits into law under the plan. Basically he wants less of everything: funding, regulation, and taxes.

4/

Lisa Murkowski of Alaska

Lisa Murkowski.
Thomson Reuters

What she's said: Murkowski was the third GOP Senator on July 18 to oppose a motion to proceed on a vote for the repeal-only bill. Murkowski also had concerns about the BCRA, though in an updated draft she was given some incentive to vote in favor of it: a guarantee of funding for Alaska to combat high premiums. Even so, she's not a guaranteed yes on the bill.

What she wants: Murkowski also supports continuing the expansion of Medicaid and keeping funding for Planned Parenthood. Murkowski was reelected in 2016.

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Mike Lee of Utah

Mike Lee.
REUTERS/Jim Urquhart

What he's said: Lee helped contribute to the Consumer Freedom Amendment added to the BCRA, but ultimately couldn't get on board with the amendment.

"After conferring with trusted experts regarding the latest version of the Consumer Freedom Amendment, I have decided I cannot support the current version of the Better Care Reconciliation Act," Lee said on July 17.

After this resistance, it appears a full version of the CFA will be voted on, though it would need 60 votes to pass. This could be enough to get Lee on board with the motion to proceed.

What he wants: Lee wants to see a quicker phaseout of the Medicaid expansion and repeal of various insurance market regulations. Lee was reelected in 2016.

6/

Shelley Moore Capito of West Virginia

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What she's said: Capito also opposed a motion to proceed to vote on the repeal-only bill.

"For months, I have expressed reservations about the direction of the bill to repeal and replace Obamacare," she said in a statement. "I have serious concerns about how we continue to provide affordable care to those who have benefited from West Virginia's decision to expand Medicaid, especially in light of the growing opioid crisis. All of the Senate health care discussion drafts have failed to address these concerns adequately."

Capito was still undecided on a more broad motion to proceed. President Trump personally pushed Capito to vote for the motion Monday night during a meeting in her home state of West Virginia.

What she wants: West Virginia has a large Medicaid population and expanded the program under the ACA. Capito has expressed desire for a seven-year phase out of the expansion. The discussion draft proposes to phase it out over four years. Capito is up for reelection in 2020.

7/

Rob Portman of Ohio

Rob Portman.
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What he's said: Portman has been critical of the BCRA and isn't on board with the repeal-only plan.

"Let's not throw in the towel. Let's actually get the reforms that we Republicans have been talking about for years, giving the states more flexibility, giving the insurance companies the ability to sell plans people want to have. None of that happens with repeal," he told Fox News on Friday.

A revised healthcare bill is expected to include an amendment that will add $100 billion for Medicaid, which Portman supports.

What he wants: Ohio was one of the states to expand Medicaid under Obamacare, so a slower phaseout would work in his favor. Additionally, the original bill supplies only $2 billion to combat the opioid crisis, less than the House's legislation — though that's since been updated to $45 billion. Portman won reelection in 2016.

8/

Ted Cruz of Texas

Ted Cruz.
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What he's said: Cruz was one of four conservatives to come out against the Senate bill in June, and has since had a hand in shaping the bill. His biggest contribution is amendment titled the " Consumer Freedom Amendment," would have allowed plans to exist that don't comply with two regulations set up under the Affordable Care Act: community rating and essential health benefits. The latter could have had a big impact on people with preexisting conditions.

The CBO hasn't scored the version of the bill that contains the CFA, so if that version goes up for a vote, it would need 60 votes to pass.

Despite this, Cruz is still likely to vote for the motion to proceed.

What he wants: Cruz would like include a full repeal of so-called essential health benefits, and more support to lower premiums. Cruz is up for reelection in 2018.

9/

Ron Johnson of Wisconsin

AP

What he's said: Johnson has been critical of the bill since June.

"A simple solution is obvious," he wrote in The New York Times. "Loosen up regulations and mandates, so that Americans can choose to purchase insurance that suits their needs and that they can afford."

Johnson, like many senators, isn't happy that he's been left in the dark on which bill could be voted on starting Tuesday. "I don't have a clue what we're gonna be voting on," Johnson said on Monday.

While he is critical of the move, Johnson is considered more likely to vote for the motion to proceed.

What he wants: A more complete repeal of Obamacare, much like Cruz, Lee, and Paul.

10/

Jerry Moran of Kansas

What he's said: Moran joined Lee in opposing the motion to proceed on a vote for the BCRA.

"There are serious problems with Obamacare, and my goal remains what it has been for a long time: to repeal and replace it. This closed-door process has yielded the BCRA, which fails to repeal the Affordable Care Act or address healthcare's rising costs. For the same reasons I could not support the previous version of this bill, I cannot support this one," Moran said in a statement on July 17.

"We should not put our stamp of approval on bad policy. Furthermore, if we leave the federal government in control of everyday healthcare decisions, it is more likely that our healthcare system will devolve into a single-payer system, which would require a massive federal spending increase."

What he wants: Moran has expressed concerns about what the healthcare bills will do to people living in rural parts of Kansas. He's also on board with the straight Obamacare repeal.

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A few more...

Arizona Sen. Jeff Flake.
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While the others are the most likely to raise objections, there are few other Republicans who could come into play depending on how the negotiations proceed.

Some lawmakers in states that expanded Medicaid, like Sens. Jeff Flake of Arizona, Tom Cotton of Arkansas, and Cory Gardner of Colorado have so far been noncommittal — though Cotton seems more in favor of repeal-without-replace. Other Republicans like Sen. Pat Toomey of Pennsylvania could raise objections to tax credits.